Gegen kept his theory mostly to himself until he found evidence to support his theories. Gegen found evidence of his theory on Hanon IV when he discovered the bones of a humanoid, CrewmanHogan, whose genetic makeup bore some similarities to his own. He was able to determine that the bones came from the shipUSS Voyager, which then he tracked down. He and his assistant Tova Veer boarded under cloak and studied the crew until they were discovered. Veer was captured while Gegen abducted Chakotay, who had been knocked out by Veer. Chakotay helped Gegen find more evidence for his theory. In fact, the Voth had evolved from Earth's hadrosaurs. Gegen's ancestors avoided extinction, developed space-faring technology, left the planet, and ended up in the Delta Quadrant. Chakotay went with Gegen back to the Voth city ship to present his evidence.

The Voth Ministry of Elders did not look kindly upon the new evidence, and charged the professor with heresy. MinisterOdala tried to force Gegen to retract his claims. Veer was threatened, and he recanted and denounced Professor Gegen. Gegen refused to retract his theories until Odala threatened to imprison the crew of Voyager for life and destroy the ship. Gegen submitted and he was relieved of duty and reassigned to a job as metallurgical scientist, a career in which he felt he would be undistinguished. However, as Chakotay departed Gegen's ship, he gave his friend a globe of Earth, and Gegen expressed his wish that, someday, all Voth would call Earth "home".

Gegen means "against" in German. Given that Gegen's findings and views ran counter to his species' doctrine, his name is either an ironic coincidence or an interesting choice by the episode's writers. The term "gegen" is often used by German and other European cinematographers for the "back light" during film lighting.

Gegen's treatment at the hands of the Ministry of Elders parallels that of Galileo Galilei by the Roman Catholic Church in the 17th century.